1. Field of the Invention
The invention generally relates to memory devices and more particularly to metadata about, and sent with, requested data.
2. Description of the Related Art
Semiconductor memories have been designed and structured to use one memory device for each bit, or small group of bits, of any individual computer word, where the word size is governed by the choice of a requesting device. Typical word sizes range from 4 to 64 bits. Each memory device typically is connected in parallel to a series of address lines and connected to one of a series of data lines. When the requesting device, for example a controlling processing unit (CPU), seeks to read from or write to a specific memory or location, an address is put on the address lines and some or all of the memory devices are activated using a separate device select line for each needed device. One or more devices may be connected to each data line, but typically only a small number of data lines are connected to a single memory device.
Data is thus provided in parallel for each memory read or write operation. For the system to operate properly, every single memory bit in every memory device must operate dependably and correctly.
In a conventional system, the CPU sends a request to a memory device, for example a dynamic random access memory (DRAM), a static RAM (SRAM) or a read only memory (ROM). The request includes command information to read data from the memory and address information that determines the addresses of the memory cells of the memory from which the data may be read. The memory evaluates the request and reads the data from the determined memory cells referring to the transferred addresses and sends the data to the CPU.
In conventional systems, the request may include a length information for requesting data with different numbers of data bits. Thus, it is possible for the requesting device to receive or read different numbers of data bits from the memory.